1. Field of the Invention
The invention relates to a sealing ring that comprises at least two segments running in a circumferential direction forming an overlapping joint.
2. Description of the Prior Art
A multiple-part sealing ring made up of three ring segments is known from the patent CH 439 897. The gaps of the ring segments form a through slot extending in the axial direction. Such sealing rings are usually arranged in pairs in series one behind the other and form a so-called packing, in order to seal the sliding surface of a body which is to be sealed, for example, a piston rod of a piston compressor. This known sealing ring has the disadvantage that to seal the through-slot in the axial direction, two sealing rings are respectively to be arranged in pairs adjacent one another. A further disadvantage is to be seen in that a pair of sealing rings arranged adjacent one another has a relatively large extent in the axial direction, which brings about an increased frictional heat. This frictional heat is moreover difficult to dissipate because the sealing ring is usually manufactured from plastic and has a low thermal conductivity, which prevents the transport of heat from the body to be sealed to an external cooling device.
It is the object of the present invention to propose a sealing ring which overcomes these disadvantages.
The sealing ring in accordance with the invention comprises a multiple part ring, which is formed by at least two ring segments, wherein the ring segments have mutual joints, which are formed overlapping in the circumferential direction of the sealing ring.
An advantage of the sealing ring in accordance with the invention is to be seen in the fact that adjacent ring segments respectively have a mutually overlapping joint, so that no straight through-slot is present between the ring segments in a direction extending vertically to the sealing ring, or as the case may be, in a direction axial to the body to be sealed. A sealing ring of this kind has an excellent seal. In a further advantageous embodiment of the sealing ring in accordance with the invention, a cover ring is arranged extending circumferentially externally about the ring segments, which covers over the joints extending between the ring segments in a radial direction from the outside and by this means seals them. The cover ring also serves to mutually stabilize the ring segments. A spring extending in the circumferential direction is advantageously arranged lying on the cover ring at the outside, as for example, a hose spring, or toroidal spring, in order to exert a force acting radially inwardly on the ring segments. The cover ring can, moreover, have a connecting element cooperating with one of the ring segments, in order to prevent a rotation of the cover ring relative to the individual ring segments.
With regard to a rod which is to be sealed, a sealing ring can be developed in such a manner that the individual ring segments have a mutual clearance extending in the circumferential direction of the sealing ring. The sealing ring undergoes progressive wear during the operation on the surface facing the rod. The sealing ring in accordance with the invention has the advantage that, due to the clearance between the individual ring segments and also the hose spring surrounding the sealing ring, the ring segments are constantly subjected to a force acting in a radial direction towards the rod, so that during the progressive wear, the clearance between the ring segments is constantly reduced, wherein the ring segments contact the rod and maintain their sealing function. Moreover, the sealing function of the sealing ring is maintained in the axial direction by means of the overlapping joints.
The portions of the ring segments overlapping one another are designed in such a manner that even when the clearance to one or more of the adjacent ring segments becomes zero, the remaining adjacent ring segments still have portions with overlapping joints. It is thereby ensured that a leakage at the joints in the axial direction does not occur at any position of the ring segments.
A sealing ring comprising at least two ring segments as well as a cover ring extending circumferentially at the outside has the advantage that, due to the combination of overlapping joint and circumferentially extending cover ring at the outside, a very good sealing action in the axial direction results, and also that only a single sealing ring is required for sealing in the axial direction, so that the sealing ring has a low constructional height in the axial direction. A further advantage of the sealing ring in accordance with the invention is to be seen in that a relatively stiff material can also be used as material for the ring segments, so that a high temperature polymer, such as, for example, modified PEEK can also be used as a material for the ring segments.
In a further advantageous embodiment, the sealing ring in accordance with the invention is designed in such a way that the mutual ring segments have no mutual clearance, with the diameter of the rod to be sealed being chosen in such a way, that a split ring seal results between the sealing ring and the rod. In a sealing ring designed in this way, the ring segments can also be made of a ceramic material, wherein the cover ring surrounding the ring segments in a circumferential direction is still made of a plastic.
A further advantage of the sealing ring is to be seen in the fact that due to its type of construction an installation of the ring with an already installed piston rod is possible and not problematic.
The following drawings describe a particular embodiment of the invention. They show: